000 00291nam a2200109Ia 4500
008 230416s9999||||xx |||||||||||||| ||und||
050 _aQ175 .C23 1963
100 _aCampbell, Donald T.
245 0 _aExperimental and quasi-experimental designs for research
260 _c1963
942 _2lcc
_cBK
999 _c4818
_d4818